The only experience I have with this type of system is at WDW, and the success seemed to depend on the op running the line. Sometimes, they would let only people with Fastpasses through for a long time and leave the regular line stopped, or vice versa. However, most of the time it worked well, I found little wrong with it.
However, instead of charging for it, I wish that they were only available to certain guests, such as season pass holders, just as the Disney system is only for people staying at the Disney resorts.
However, I will still go to SFGAm and I am sure I will still have an excellent time, just like always. I really don't mind waiting as long as I'm with someone to talk to.
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As a human being I reserve the right to do something something stupid.
-Ed